If the stuttering is genuinely from the difference in frame rate between 50 and 60Hz, then you may be stuck with it, short or re-running AV Wizard each time and changing the refresh rate of your TV (although it would be nice if LMCE allowed you to configure 2 different valid screen setups and auto switched between them based on the content
Frame rate conversion is really
ugly. Converting from film at 24Hz to PAL/DVB at 25Hz frame rate is not an issue - they are so close, they just don't bother, and the film replays very slightly faster. But converting from film at 24Hz to NTSC/ATSC at 29.9blahHz is too big a jump just to replay as the speed up and pitch bend is noticable. So comes the ugliness of 3:2 Pull down conversion, and I'm sure many N.A.s would be familiar with the occasional jerkiness of films played on TV from this.
There are more sophisticated methods used these days, not dissimilar to the interpolation used in some forms on deinterlacing, however they are very heavy duty and would certainly need substantial hardware acceleration. Something I am not sure whether consumer GPUs offer currently (probably the high end ones?) but its questionable whether those features are exposed through the VDPAU API at this point!!